Add patches for ADC peripherals

Add a patch to fixup a few registers in the ADC peripheral
for ATmega328P, ATmega32U4, ATmega1280, and ATmega64.

Add patch for SPI device

atmega328p: Add missing patches

This commit adds patches for ATmega328P by copying the commons from ATmega32U4, omitting PLL because the 328p lacks that feature (#11)

atmega328p: Add patch & fix ACSR access mode

Signed-off-by: Rahix <rahix@rahix.de>